Echocardiography in the evaluation of systolic murmurs of unknown cause

Systolic murmurs are common, and it is important to know whether physical examination can reliably determine their cause. Therefore, we prospectively assessed the diagnostic accuracy of a cardiac examination in patients without previous echocardiography who were referred for evaluation of a systolic murmur.

In 100 consecutive adults (mean [+/- SD] age of 58 +/- 22 years) who were referred for a systolic murmur of unknown cause, the diagnostic accuracy of the cardiac examination by cardiologists (without provision of clinical history, electrocardiogram, or chest radiograph) was compared with the results of echocardiography.

The echocardiographic findings included a normal examination (functional murmur) in 21 patients, aortic stenosis in 29 patients, mitral regurgitation in 30 patients, left or right intraventricular pressure gradient in 11 patients, mitral valve prolapse in 11 patients, ventricular septal defect in 4 patients, hypertrophic obstructive cardiomyopathy in 3 patients, and associated aortic regurgitation in 28 patients. In 28 (35%) of the 79 patients with organic heart disease, more than one abnormality was found; combined aortic and mitral valve disease was the most frequent combination (n = 22). The sensitivity of the cardiac examination was acceptable for detecting ventricular septal defect (100% [4 of 4]), isolated mitral regurgitation (88% [26 of 36]), aortic stenosis (71% [21 of 29]), and a functional murmur (67% [14 of 21]), but not for intraventricular pressure gradients (18% [2 of 11]), aortic regurgitation (21% [6 of 28]), combined aortic and mitral valve disease (55% [6 of 11]), and mitral valve prolapse (55% [12 of 22]). In 6 patients, the degree of aortic stenosis was misjudged on the clinical examination, mainly because of a severely diminished left ventricular ejection fraction. Significant heart disease was missed completely in only 2 patients.

In adults with a systolic murmur of unknown cause, a functional murmur can usually be distinguished from an organic murmur. However, the ability of the cardiac examination to assess the exact cause of the murmur is limited, especially if more than one lesion is present. Thus, echocardiography should be performed in patients with systolic murmurs of unknown cause who are suspected of having significant heart disease.